Today's fleet of general aviation aircraft consist of primarily of airplanes that are 15-20 years old. The majority of single and light twin engine aircraft manufacturers discontinued production many years ago, with only a few recently coming back into the marketplace. Also, a high percentage of general aviation aircraft today are home built kit airplanes. Almost without exception, the instrument lighting on these aircraft is notoriously bad. The March 1996 publication of The Aviation Consumer, summed it up best in their article "Light to Fly By" by saying "Looking over the fleet, you'd think that airplanes are designed and apparently supposed to fly only in the daytime. Sure, the placard may say, "Day and night operations," but the night lighting is so shoddy that it's nearly worthless." pg. 19.
If any mode of transportation requires good instrument lighting for one's safety, flying is certainly it. Lighting products are abundant in aviation consumer catalogs. These products consist of flashlights to stick in your pocket, flashlights to attach to your headset and even flashlights to hold in your mouth while you fly. Dropping the flashlight between the seats can result in a panic. Experienced pilots have told stories of having passengers light matches while flying to illuminate instruments.
One of the reasons many aircraft instruments are not properly lighted, such as is seen in automobile dash panels, is that aircraft instruments give readings which are related to the change of air pressure. Most of the instruments are therefore, tightly sealed, and do not allow for having an internal lighting system in the instrument, especially one that has an easily replaced bulb. Internally lit instruments are available, but they are expensive ($100-$200 more) and replacing a bulb is difficult, time consuming and expensive.
Currently used methods to illuminate instruments include hard-mounted snaking lights which point back at the instrument panel, but which get in the way of the pilot and also spoil the aesthetic look of the original aircraft instrument panel. This is of particular concern for vintage aircraft, whose value and aesthetics are closely correlated. Other products which attempt to improve the lighting of instruments include post lights, which are very small lights that replace an instrument mounting screw. The wiring for post lights is very fine and fits inside a hollow-mounting screw housing, making the wiring very susceptible to electrical shorts. With this technique it is difficult to evenly light an instrument, and most instruments will require two or more post lights. This type of lighting system has a protruding lamp which also tends to get bumped and broken. Cross-threading the plastic assembly can be an installation problem and the cost of the system is approximately $40-$50 per miniature post assembly. Internally lighted instruments seem to be an attractive solution, but, as mentioned above, internally lighted instruments are expensive to purchase and when a bulb burns out, the instrument has to be removed and opened to replace the bulb, and re-calibrated if the pressure seal is broken, also expensive. Also, the quality of lighting varies from manufacturer to manufacturer, with lighting from different manufacturers creating a mis-match and a wide variety of illumination intensities. Other attempts to improve lighting include electroluminescent panels. Typically the cost to light a panel with this type of lighting is 20 percent of the cost of a new panel, a cost that is too prohibitive. Also, the illumination intensity of the electroluminescent panels' tends to diminish with age. The half-life of an electroluminescent panel is around 800 hours. Another more recent attempt to light instruments is with a product commercially available under the name, Nu-Light. The Nu-Light is an acrylic light wedge that fits between the instrument and the panel. Two small incandescent bulbs are imbedded in the top of the light-wedge. Sixty percent of the light is directed at the top half of the instrument. The Nu-Light does require special wiring for each instrument and the acrylic wedge is fragile and easy to crack during assembly. None of the above-mentioned lighting methods address the problem of illuminating switches, warning placards and safety checklist.